We noticed a weird issue on our WP 4.9.10 blog pages when going to 1st page. Right now we can go to 2nd or 3rd page by clicking the page numbers but saw that it gives 301 code when going to 1st page but gets 200 response code for 3rd or 4th, and so on.
Clicking the Previous button on the blog pagination at the bottom takes you to a page with hosted server name.
This sometimes happens when clicking 1, 2, 3, when you are on page 4 (and so forth for other pages).
At the end we get site can't be reached because WP blog is set up inside DMZ with reverse proxy set up.
We have not customized any PhP code other than making few changes to admin panel settings and http conf changes to work with reverse proxy and https only.